Black High School Graduation Caps. Gradshop offers superior quality graduation caps for all high school graduates at affordable prices to meet your budget for your graduation ceremony. The distinctive black mortarboard cap is made of shiny tricot fabric and measures 9.4"sq. It is designed with elastic at the sides for additional grip and comfort. Checkout our black tassels as well as many different color tassels and order on line for the best discounts and great deliveries.